The present invention relates to a method and an apparatus for severing or damaging an unwanted plant by e.g. combining an optical image recognition system capable of differentiating between different types of plants and a light generating means for exposing the plant to electromagnetic radiation.
In U.S. Pat. No. 5,296,702, a system is provided for plant recognition. The system disclosed in U.S. Pat. No. 5,296,702 comprises a targeting system for applying herbicides to individual plants so as to reduce the use of herbicides. The system is capable of differentiating between different plants so that only a predetermined type of plants, e.g. an unwanted plant, will be exposed to herbicides.
A disadvantage of the system disclosed in U.S. Pat. No. 5,296,702 is that the use of herbicides is not avoided.
It is an object of the present invention to provide a method and an apparatus capable of severing or damaging unwanted plants without using herbicides.
In accordance with the present invention, an apparatus and a method are provided for differentiating between different types of plants to allow identification of, and thus selective elimination or treatment of, individual plants. In the present invention, the positioning of and the output power of at least one light generating means is controlled on the basis of information from an image recognition system which is capable of differentiating between different plants.
The image recognition system provides an output signal for each different plant being imaged and identified. A controller analyses the output signal from the image recognition system, and assuming the imaged plant is a utility plant, no action is taken with respect to the plant. In the case where an unwanted plant has been identified, information relating to the position, and optionally the type of plant, is transmitted to a control system. The control system directs at least one light beam, such as with a plant-dependent intensity, toward the unwanted plant in order to damage or actually sever the plant. Alternatively all plants not recognised as utility plants may be radiated.
An advantage of the present invention is that the use of herbicides is completely avoided.
A further advantage of the present invention is related to the fact that it may operate under a wide variety of weather conditions including windy conditions, bright sunlight, artificial illumination or even total darkness. Especially the operability under windy conditions is an advantage, since the use of herbicides under such conditions normally results in overxe2x80x94spay.
The present invention brings the farmer close the goal where:
no unwanted plants are over-looked, and
the use of herbicides is completely avoided
More specifically, in a first aspect the invention relates to an apparatus for severing or damaging plants, the apparatus comprising:
means for generating image data representing at least part of a plant,
means for analysing the image data and for determining whether the plant is one of a number of predetermined plants or types of plants, and, from that determination, whether the plant is to be severed or damaged,
severing or damaging means adapted to generate and direct a beam of electromagnetic radiation toward the plant in a manner so that at least part of the plant is severed or damaged.
As will be clear from the following, it may be over-kill to actually fully sever the unwanted plants, as a thermal damaging thereof may retard the growth sufficiently for the utility plants to xe2x80x9cout growxe2x80x9d the unwanted plants and thereby prevail. Thermal damaging may be a local heating of a sufficiently large or vital part of the plant. A vital part of the plant is the stem, and a local heatingxe2x80x94such as one leading to cell destructionxe2x80x94of a part thereof will prevent or reduce the liquid led from the root to the leaves which again will kill or retard the plant. This will be described in more detail further below.